Loss separation for dynamic hysteresis in magnetic thin films

TL;DR

This paper presents a generalized theory of dynamic hysteresis in ferromagnetic thin films based on loss separation, validated through simulations and experimental data, unifying diverse observations across materials.

Contribution

It extends the loss separation theory from bulk metals to disordered magnetic thin films, explaining dynamic hysteresis universally regardless of damping mechanisms.

Findings

Theory matches experimental data across various thin films.

Simulations confirm the applicability of loss separation in disordered systems.

Power loss dependence on field rate fits all tested data.

Abstract

We develop a theory for dynamic hysteresis in ferromagnetic thin films, on the basis of the phenomenological principle of loss separation. We observe that, remarkably, the theory of loss separation, originally derived for bulk metallic materials, is applicable to disordered magnetic systems under fairly general conditions regardless of the particular damping mechanism. We confirm our theory both by numerical simulations of a driven random--field Ising model, and by re--examining several experimental data reported in the literature on dynamic hysteresis in thin films. All the experiments examined and the simulations find a natural interpretation in terms of loss separation. The power losses dependence on the driving field rate predicted by our theory fits satisfactorily all the data in the entire frequency range, thus reconciling the apparent lack of universality observed in different materials.